High-performance composite solid-state electrolyte reinforced with cellulose acetate for solid-state lithium batteries

Solid-state lithium batteries, offering high energy density and enhanced safety, are widely regarded as the leading candidates for next-generation battery technology. Among the various solid-state electrolyte systems, polyethylene oxide (PEO)-based composite solid-state electrolytes (CSEs) integrate the merits of multiple electrolyte types, positioning them among the most promising options for practical application. To further optimize and enhance the integrated performance of PEO-based CSEs, this study presents a cellulose acetate (CLA)-reinforced PEO-Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) CSE. CLA provides additional Li + transport pathways within the PEO matrix and promotes the dissociation of LiTFSI. As a result, the fabricated CSE exhibits excellent Li + conductivity (2.72 × 10 −4 S cm −1 ) and a high Li + transference number (0.62) at 60 °C. Moreover, the CLA network imparts superior mechanical robustness to the CSE, thereby maintaining the structural integrity of the electrolyte during battery operation and enhancing cycling stability. The Li-Li symmetric battery incorporating this electrolyte achieves stable cycling for over 4200 h at a current density of 0.1 mA cm −2 . Furthermore, the LiFePO 4 (LFP) solid-state battery delivers a high initial discharge capacity of 158.8 mAh g −1 at 0.2 C and 60 °C, exhibiting a capacity retention of 93.0% after 100 cycles. At 1 C, the battery attains a high initial capacity of 150.3 mAh g −1 and maintains a capacity retention of 80.6% after 600 cycles, while also achieving stable cycling for 1200 cycles at 2 C. This work provides a promising strategy for the application of cost-effective composite solid electrolytes with superior comprehensive performance in solid-state lithium batteries.